Tower excavator



G. B. MASSEY TOWER EXGAVATOR May 5, 1931..

Filed Nov. 5, 1930 Z7ZZJ67ZZ07" Geo/ ye 5. WZasse Patented May 5, 1931 I UNITED STATE GEORGE B. MAs'sEY, or CHICAGO, ILLINoIs TOWER EXCAVATOR Application filed November 5, 1930 Serial No; 493,578.

This invention relates to excavator'sof the taken out of the track cable sufficiently to class in which a drag bucket is" operated beperinit the bucket to emptyon the levee tween spaced towers which, when in use, for and thento run back above the groundtoward example in levee construction work, are the starting position, due to the winding up 4 5 shiiftable along parallel lines. The bucket of the haul-back line, as assisted by gravity; 6'5 isfilledas it is dragged toward the head tower When the bucket" has reached the starting and is returned empty and abovethe ground point for the digging stroke the tracklcable toward the tail tower. is again slacked, and the bucket is drawn The objects of this invention are to provide along the ground toward the head tower by I 10 iinprovenientsin the bucket suspension means thedrag line. v 66 and particularly with reference to'the return It is found in the use of such equipment of the bucket to the starting position after that during the return motion of the bucket each digging operation. The purposes of the under the back-haul line, this line has a tendimprovements are to rapidly return the'buekency towhip and break. The improved con- 5 et tothe'sta'rting position While avoiding the struction avoids the use ofa back-haul line. 65 use of aback-haul cable and'breakages thereand its wind-up drum by theprovision of a of; and to decrease the number of winding pair of diverging track cables which may be drums generally required in tower excavators. wound upon the same druin. These cables The objects, of the invention are acc'o'im pass Over widely spaced sheaves near, the top o pl'i's'hed by a; construction as shown the of the main tower, and then converge toward iii drawings, in which':-- the supporting trolleys for the bucket, and

Figure I is a diagramm tic side view of a from there run substantially parallel to the tower x a 'w'a'tor provided with the present sheaves or anchoring-means onthe tail tower. improvements and shows'a section of a levee When there; 1s slackin the track cables, as and a borrow pit from which the l'e'v'eebui'kL 1s the case durlng the dig 'lng stroke, the drag 75 ingr'naterial is taken. line may freely pull the bucket along the pair Figi 2is a plan view'of the tower excavator of cables without nucli Change in resistance q jpm nt'shown'in Figure 1, due to the change in the angle of divergence FigISis fra mentar detailview takenion 0f the track cables, between the bucket and 3b tlieline 3'3 of Figural. the main tower as the bHCkGt HlOW-JS toward Eig. at isan enlarged perspective view of the main tower. At the endof the stroke,as

a drag bucket and its supporting means. the bucket is dragged toward the top of the 7 Tower excavators generally comprise a levee, the track cables are drawn to a more head tower and a tail tower which may be taut position which causes the rear end of the spacedapart' some 500' or 600' feet with a bucket to be lifted, and the bucket empties. 35 cable extended between the towers from The further tensioning of the track cables which a drag bucket is suspended. As the and gravity causes the bucket to run back 7 work progresses, the towers under their own along the cables to its digging point. The power are shifted along parallel lines and tenslon on these diverging lines passing 40 for this purpose are frequently provided with through the horizontally spacedtrolleys from the crawler type of propulsion means- The which the bucket is suspended, forces the main cable extending between the towers bucket backwardly along the parallelporserves as a track for a trolley from which the tions of the track cable toward the start of bucket is suspended. This cable passes over its digging path. This general arrangement a sheavenear the top of the Inast of the inain may be modified by having one only of these tower and runs down to" a winding drurn cables serve as a supporting track for the which isopera'ted as required to allow slack bucket and the other cable utilized mainly iii the cable so that'the' teeth of thebuc'ket for forcing the bucket backward. In either Iiiay'engage the ground during'the fillingop case a quick return is efiected by tensioning eration, at the end of which time slack is the cables.

The tower excavator equipment, shown in the drawings, varies from the customary arrangement mainly in having a pair of diyerging track cables 1, rather than the single track cable usually employed. The im proved construction also dispenses with the haul-back line for the bucket, including the necessary sheaves on the tail and head towers and the winding drum therefor.

Such parts of the construction illustrated, as are now well known in this art, include a head tower 2 and a tail tower 3, each generally provided with propulsion means so that they may be shifted as required along the line of work. The head tower is equipped with power driven wind-up drums 4 and 5 which are controlled from an operators cage 6 carried by the mast 7 in position where the operator may View the action of a bucket 8. This bucket, in operation, is drawn toward the tower 2 by a drag line 9 passing over sheave 10 on mast 7 and from thence to the wind-up drum 4:.

The new parts of the equipment are the two track cables 1 which, at the tail tower, are either anchored thereto or led from a windupdrum 11 over. sheaves 12 which are close together on tower 3 and from these sheaves lead to horizontally spaced and more widely spaced sheaves 13 carried by a crosstree 14 secured to the upper end of mast 7. The track cables 1 lead from the sheaves 13 to a single wind-up drum 5.

The drag bucket 8 is of well-known construction and is supported at its rear end by cables 15 from which it is suspended from a trolley 16, arranged to run along the track cables 1. It is customary to use but a single trolley and a single track cable.

The chains 15 are connected by a bar 17 near the trolley 16. The trolleys are spaced apart substantially the same as the spacing of sheaves 12 on tower 3. The track cables extend parallel from tower 3 to trolleys 16 which serve to hold the track cables together at the point of the trolleys wherever the bucket may be along the track cables. From the trolleys the track cables diverge to the horizontally spaced sheaves 13 on the head tower 2.

' In the operation of this equipment, in the filling of the bucket, the latter is drawn from a position near the tail tower toward the head tower by the drag line 9, asthe latter is wound upon rotating drum 4. During the filling operation, sufficient slack is permitted in track cables 1 to allow for the required enagement of the teeth of the bucket with the ottom of the borrow pit 18. The bucket is drawn over the ground while filling and transporting the load up the levee to the desired place for dumping, when the hauling on the drag line is stopped and the track cables are pulled up, thus raising the rear end of the bucket and emptying it. The bucket is cables to the starting position.

shown in such position by the broken lines in Fig. 1.

In order to cause the bucket to return to its starting position more rapidly than by gravity alone, the track cables 1 are tensioned by a further rotation of winding drum 5. This tensioning of the track cables, which diverge from the trolley 16 to the sheaves 13, forces the trolleys and the bucket suspended therefrom to run backwardly along the track lVith this arrangement of diverging track cables, a back-haul line is unnecessary. The backhaul line generally runs from the rear end of the bucket to a sheave on the tail tower and from thence to a sheave on the head tower to a winding drum on the latter. In order to return the bucket to the starting position as rapidly as possible, it is customary to rotate the back-haul winding drum at a comparatively high rate of speed, such as to cause whipping of the back-haul line and occasional breakage thereof.

Such an arrangement is now dispensed with, as the bucket may be more rapidly returned and with less breakage by the spreading action on trolley 16 when the diverging track cables 1 are tensioned.

Although but one specific embodiment of this invention is herein shown and described, details thereof may be modified without departing from the claims.

I claim:

1. In a tower excavator, head and tail towers, a pair of horizontally spaced track cables extending between said towers, supporting means on the head and tail towers for the track cables, said supporting means being more widely spaced on the head tower than on the tail tower, a pair of trolleys arranged to run upon said trackcables, a drag bucket suspended from said trolleys, a drag line attached to the drag bucket and extending to winding means on the head tower, and means on one of said towers for simultaneously tensioning the track cables.

2. In a tower excavator, head and tail towers, a pair of horizontally spaced track cables extending between said towers, supporting means on the head and tail towers for the track cables, said supporting means being more widely spaced on the head tower than on the tail tower, a pair of trolleys arranged to run upon said track cables, a drag bucket suspended from said trolleys, a drag line attached to the drag bucket and extending to winding means on the head tower, and means on the head tower for simultaneously tensioning or slackening the track cables.

3. In a tower excavator, head and tail towers, a combined track cable and bucket return equipment comprising a pair of cables extended between said towers, a drag bucket, trolleys for running on said cables and from which the bucket is suspended, said cables which the bucket is suspended, said cables 7 being substantially parallel from the trolleys to the tail tower, and diverging from the trolleys to separate sheaves on the head tower, said sheaves being spaced apart horizontally to provide a greater horizontal distance between the same to the distance between the trolleys for supporting the bucket.

Signed at Chicago this first day of N0- velnber, 1930.

GEORGE B. MASSEY. 

